Curved waveguide and head-mounted display

Abstract

The invention discloses a curved waveguide and a head-mounted display. The curved waveguide comprises at least one curved waveguide substrate, a coupling-in area and a coupling-out area, wherein the coupling-in area and the coupling-out area are located on at least one side of the curved waveguide substrate; in the same curved waveguide substrate, the coupling-in area, the coupling-out area and the area between the coupling-in area and the coupling-out area are optical functional areas, and the curvature normal of the optical functional areas is compared with one point; the coupling-in area is used for coupling image light rays emitted by an optical machine into the curved surface waveguide substrate, and the image light rays are totally reflected in the curved surface waveguide substrate and are transmitted to the coupling-out area; the out-coupling region is located on a propagation path of the image light and is used for coupling the image light out of the curved waveguide substrate. Compared with a traditional lens type planar waveguide sheet, the planar waveguide sheet has a curved surface display structure, the available area of a curved surface waveguide coupling-out area is increased, the receivable range of a user image is larger, and the planar waveguide sheet has a better application prospect.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of display technology, and in particular to a curved waveguide and a head-mounted display. Background Art

[0002] Augmented Reality (AR) is a technology that integrates the real world and virtual information. AR display systems usually include a micro-projector and an optical display screen. The pixels on the micro-display are projected into the user's pupils through the optical display screen. At the same time, the user can see the real world through the optical display screen. The micro-projector provides virtual content for the device, and the optical display screen is usually a transparent optical component. Optical waveguide is a realization path for optical display screens. When the refractive index of the transmission medium is greater than that of the surrounding medium and the incident angle in the waveguide is greater than the critical angle of total reflection, light can be transmitted in the waveguide without leakage, and total reflection occurs. After the light from the projector is coupled into the waveguide, the light continues to propagate the image losslessly in the waveguide until it is coupled out by the subsequent structure.

[0003] At present, electric vehicles have become a convenient and commonly used means of transportation. Drivers need to wear helmets when riding electric vehicles, and they need to lower their heads to check relevant information during riding, which may lead to potential traffic accident risks. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a curved waveguide and a head-mounted display, which has a curved display structure compared to a traditional lens-type flat waveguide, increases the available area of ​​the curved waveguide outcoupling region, and has a larger receivable range of user images, thus having better application prospects.

[0005] In a first aspect, an embodiment of the present invention provides a curved waveguide, comprising at least one curved waveguide substrate and an in-coupling region and an out-coupling region located on at least one side of the curved waveguide substrate;

[0006] In the same curved waveguide substrate, the coupling-in region, the coupling-out region and the region between the coupling-in region and the coupling-out region are optical functional regions, and the curvature normal lines of the optical functional regions intersect at one point;

[0007] The coupling-in region is used to couple the image light emitted by the optical machine into the curved waveguide substrate, and the image light is transmitted to the coupling-out region by total reflection in the curved waveguide substrate; the coupling-out region is located on the propagation path of the image light, and is used to couple the image light out of the curved waveguide substrate; the coupling-out region includes n coupling-out reflection surfaces, wherein n≥2, and n is a positive integer;

[0008] The n out-coupling reflection surfaces are sequentially located on the propagation path of the image light, and are used to couple the image light out of the curved waveguide substrate by partial reflection.

[0009] Optionally, the angle between the ith out-coupling reflection surface among the n out-coupling reflection surfaces and the surface normal passing through its reflection point is θ i :

[0010] θ i =θ i-1 +θ / 2;i=2,3,4,...,n;

[0011]

[0012] Among them, θ 0 is the angle between the image light and the normal after entering the curved waveguide substrate, r is the radius of curvature of the inner side of the curved waveguide substrate, and d is the thickness of the curved waveguide substrate; θ is the central angle of the image light with the same field of view corresponding to the reflection points of two adjacent out-coupling reflection surfaces inside the curved waveguide substrate. As the value of i gradually increases, the i-th out-coupling reflection surface gradually moves away from the coupling-in area.

[0013] Optionally, a filter film is coated on the surface of the outcoupling reflective surface, and the filter film includes a monochromatic filter film or a filter film that transmits at least two colors.

[0014] Optionally, along the propagation direction of the image light in the curved waveguide substrate, the reflectivities of the n out-coupling reflection surfaces gradually increase.

[0015] Optionally, the curved waveguide includes a plurality of curved waveguide substrates stacked in layers;

[0016] The optical functional areas of at least two of the curved waveguide substrates have different curvature radii, and the curved waveguide substrates with different curvature radii propagate image light of different wavelengths.

[0017] Optionally, along the direction in which the image light beam is coupled out of the curved waveguide substrate, the curvature radius of the optical functional areas of the plurality of curved waveguide substrates gradually decreases, and the wavelengths propagated by the plurality of curved waveguide substrates gradually decrease.

[0018] Optionally, along the direction in which the image light is coupled out of the curved waveguide substrate, the thicknesses of the plurality of curved waveguide substrates gradually increase.

[0019] Optionally, a phase modulation device is also included, and the light of the same field of view angle emitted by the optical machine is modulated by the phase modulation device and then incident on the coupling-in area, so that the transmission angle of the light of the same field of view angle after being coupled into the curved waveguide substrate is the same.

[0020] Optionally, the phase modulation device includes a focusing lens, which is arranged in the coupling area or the exit pupil position of the optical machine; or, the right-angle surface of the turning prism of the optical machine is a free-form surface, and the free-form surface is implemented as the phase modulation device.

[0021] In a second aspect, an embodiment of the present invention further provides a head mounted display, comprising the curved waveguide provided in the first aspect, and further comprising at least one optical machine and at least one image collector;

[0022] The image collector is used to acquire the surrounding image, and transmit the surrounding image through the optical machine to be displayed at the output end of the curved waveguide.

[0023] The curved waveguide provided in the embodiment of the present invention has a curved display structure compared to the traditional lens-type flat waveguide, which increases the available area of ​​the curved waveguide outcoupling region, and the receivable range of the user image is larger. The curvature radius of the curved waveguide substrate and the arc length can be set according to the needs of the actual scene. In the helmet display, more possibilities can be provided for the installation position of the optical machine and the circuit board, making it more beautiful and more flexible in design, with less pressure on the user's ears, and having better application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0025] Figure 1 A schematic diagram of the structure of a curved waveguide provided in an embodiment of the present application;

[0026] Figure 2 A schematic diagram of the tilt angle of an out-coupling reflective surface provided in an embodiment of the present application;

[0027] Figure 3 A schematic diagram of the optical path of a dimming structure provided in an embodiment of the present application;

[0028] Figure 4 A schematic diagram of the optical path of another dimming structure provided in an embodiment of the present application;

[0029] Figure 5 A schematic diagram of the structure of another curved waveguide provided in an embodiment of the present application;

[0030] Figure 6 A schematic diagram of the structure of another curved waveguide provided in an embodiment of the present application;

[0031] Figure 7 A side view of a head mounted display provided in an embodiment of the present application;

[0032] Figure 8 A top view of a head-mounted display provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be fully described below in combination with the drawings in the embodiments of the present invention through specific implementation methods. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work fall within the protection scope of the present invention.

[0034] Example

[0035] An embodiment of the present invention provides a curved waveguide. Figure 1 This is a schematic diagram of the structure of a curved waveguide provided in an embodiment of the present application. Figure 1 As shown, the curved waveguide provided by the embodiment of the present invention includes at least one curved waveguide substrate 10 and a coupling-in region 20 and a coupling-out region 30 located on at least one side of the curved waveguide substrate 10; in the same curved waveguide substrate 10, the coupling-in region 20, the coupling-out region 30 and the region between the coupling-in region 20 and the coupling-out region 30 are optical functional regions, and the curvature normal of the optical functional region is relative to a point; the coupling-in region 20 is used to couple the image light S emitted by the optical machine into the curved waveguide substrate 10, and the image light S is transmitted to the coupling-out region 30 by total reflection in the curved waveguide substrate 10; the coupling-out region 30 is located on the propagation path of the image light S, and is used to couple the image light S out of the curved waveguide substrate 10.

[0036] Exemplary, combined Figure 1, the curved waveguide provided in the embodiment of the present invention includes a curved waveguide substrate 10 as an example for explanation, the curved waveguide substrate 10 can be an optical glass substrate or a resin substrate, the thickness is between 0.5mm-3mm, the concave surface of the curved waveguide substrate 10 is defined as the first surface M1, and the convex surface is defined as the second surface M2, and the coupling-in region 20 can be set on one side of the first surface M1 or the second surface M2 of the curved waveguide substrate 10, and the coupling-out region 30 can be set in the central area of ​​the first surface M1 and the second surface M2, and the area of ​​the coupling-out region 30 can be reasonably set according to the size of the user's observation area. It should be noted that the coupling-in region 20, the coupling-out region 30, and the area between the coupling-in region 20 and the coupling-out region 30 are set as optical functional areas, and the curvature radius R of the optical functional areas is set to be the same. Through this setting, it is conducive to ensuring that the light enters the curved waveguide substrate 10 and is transmitted by total reflection at a constant reflection angle in the curved waveguide, and the transmission is aberration-free. The curvature radius R of the outer curved surface of the optical functional area of ​​the curved waveguide substrate 10, the curvature radius r of the inner curved surface, and the length of the curved surface can be set according to the needs of the actual scene, and the curvature radius of the non-optical functional area of ​​the curved waveguide substrate 10 can be adjusted as needed. For example, in a helmet display application, the curvature radius of the curved waveguide substrate 10 needs to meet the driver's head wearing comfort requirements.

[0037] The coupling-in region 20 includes a diffractive optical element. For example, a one-dimensional grating, such as a straight tooth grating, a blazed grating, a slanted tooth grating, a volume holographic grating, etc., can be set in the coupling-in region 20; the coupling-in region 20 can also include a geometric optical element. For example, a coupling-in prism or a coupling-in bevel, etc. can be set in the coupling-in region 20. The image light S emitted by the optical machine 100 is coupled into the curved waveguide substrate 10 from the coupling-in region 20. The image light S is totally reflected between the first surface M1 and the second surface M2 in the curved waveguide substrate 10 and transmitted to the coupling-out region 30. The coupling-out region 30 can include a geometric optical element, such as a reflective layer, a reflective prism, etc., which is used to break the total reflection transmission of the image light S and couple the image light S out of the curved waveguide into the human eye. In order to adapt to the user's wearing and use, the coupling-out region 30 can be set to couple the image light S from the first surface M1 to the user's viewing area.

[0038] Among them, the image light S emitted by the optical machine can provide relevant auxiliary information for the driver wearing a helmet (curved waveguide), such as navigation information, road condition information, etc., and project this information into a virtual image, which is displayed at a certain distance in front of the driver, so that the driver can obtain it in a head-on state, which is conducive to reducing potential traffic accidents and improving driving safety.

[0039] Furthermore, the outcoupling region 30 is provided to include n outcoupling reflection surfaces 31, wherein n≥2, and n is a positive integer; the n outcoupling reflection surfaces 31 are sequentially located on the propagation path of the image light S, and are used to couple the image light S out of the curved waveguide substrate 10 by partial reflection. The outcoupling light is reflected by the waveguide surface an odd number of times, that is, the image light is partially reflected by the outcoupling reflection surface in the process of being reflected from the inner curved surface back to the outer curved surface and outcoupling the curved waveguide substrate 10.

[0040] Specific, combined Figure 1 As shown, n out-coupling reflection surfaces 31 are embedded in the curved waveguide substrate 10 corresponding to the out-coupling area 30, and the n out-coupling reflection surfaces 31 are sequentially arranged along the propagation direction of the image light S. The out-coupling reflection surfaces 31 have a certain transmittance-reflection ratio for the image light S, and couple the image light S out of the curved waveguide substrate 10 by partial reflection. Exemplarily, for example, the transmittance-reflection ratio of the out-coupling reflection surface 31 for the image light S is 70:30, 50:50, etc.

[0041] The transmittance-reflection ratio refers to the ratio of the transmittance and reflectance of the out-coupling reflective surface to the image light. The transmittance-reflection ratios of the n out-coupling reflective surfaces 31 to the image light S may be the same or different.

[0042] In addition, if the image light of each field of view angle coupled out through the out-coupling area is not parallel light, the distances of the virtual images observed by the user's two pupils at different pupil positions are inconsistent, that is, there are breaks and intersections between the virtual images, which will cause the driver to feel dizzy during the head swinging process. Since the image light on the curved surface of the curved waveguide substrate that is farther away from the coupling-in area has a greater deviation angle when it is emitted, the range of the out-coupling area will be limited, which is not conducive to increasing the receivable range of the user's image. In order to ensure that the light of the same field of view angle can be emitted nearly parallel to enter the user's two pupils and expand the out-coupling area, the embodiment of the present application further adopts a design of correcting the emission deviation angle for the n out-coupling reflection surfaces in the out-coupling area.

[0043] In summary, the curved waveguide provided by the present invention has a curved display structure compared to the traditional lens-type flat waveguide, which increases the available area of ​​the curved waveguide outcoupling region, and the receivable range of the user image is larger. The curvature radius of the curved waveguide substrate and the arc length can be set according to the needs of the actual scene. In the helmet display, more possibilities can be provided for the installation position of the optical machine and the circuit board, making it more beautiful and more flexible in design, with less pressure on the user's ears, and having better application prospects.

[0044] Further, the angle between the i-th out-coupling reflection surface among the n out-coupling reflection surfaces and the surface normal passing through its reflection point is set to θ i :

[0045] θ i =θi-1 +θ / 2;i=2,3,4,...,n;

[0046]

[0047] Figure 2 A schematic diagram of the tilt angle of a coupling-out reflective surface provided in an embodiment of the present application. Figure 2 As shown, the out-coupling region 30 includes a first out-coupling reflection surface 311 and an n-th out-coupling reflection surface 31n. The first out-coupling reflection surface 311 is located on a side close to the in-coupling region 20, and the n-th out-coupling reflection surface 31n is located on a side of the first out-coupling reflection surface 311 away from the in-coupling region 20. The angle between the first out-coupling reflection surface 311 and the normal line of the curved surface passing through its reflection point is θ 1 The angle θ between the i-th outgoing reflection surface 31n and the curvature normal line passing through its reflection point n for:

[0048] Θ i =θ i-1 +θ / 2;i=2,3,4...,n;(1.1):

[0049]

[0050] Among them, θ 0 is the angle between the image light and the normal after entering the curved waveguide substrate 10, r is the radius of curvature of the inner side of the curved waveguide substrate 10, d is the thickness of the curved waveguide substrate 10, and r+d is the radius of curvature of the outer side of the curved waveguide substrate 10; θ is the central angle corresponding to the reflection points of the image light at the same field of view at two adjacent out-coupling reflection surfaces inside the curved waveguide substrate 10, and as the value of i gradually increases, the i-th out-coupling reflection surface gradually moves away from the coupling-in area.

[0051] Specific, combined Figure 2 As shown, i=2 is set, and the adjacent first out-coupling reflection surface 311 and the second out-coupling reflection surface 312 are taken as an example for explanation, and the angle between the first out-coupling reflection surface 311 and the surface normal P1 passing through its reflection point is set to θ 1 , combined with formula (1.1) and (1.2), the angle between the second out-coupling reflection surface 312 and the surface normal P2 passing through its reflection point is θ 2 ;

[0052]

[0053] By analogy, the angle between the third outgoing reflection surface (not shown in the figure) and the surface normal passing through its reflection point is θ 3， θ 3 =θ 2+θ / 2, the angle between the normal line of the nth outgoing reflection surface (not shown) passing through its reflection point is θ n， θ n =θ n-1 +θ / 2, that is, by modulating the angle between the inclination direction of the out-coupling reflection surface 31 and the surface normal, the angle gradually increases in the direction away from the coupling-in area 20, and the amount of change is θ / 2. Through this setting, the angle between each out-coupling reflection surface and the surface normal is different, so as to correct the outgoing light of the same field of view angle to be approximately parallel, so that the light of the same field of view angle can be nearly parallel to enter the user's pupils, which is beneficial to expand the exit pupil area of ​​the out-coupling area.

[0054] In addition, since the exit pupil of the light source of the optical machine usually has a certain area, the actual incident angles of the parallel light S' at the same angle in the coupling region 20 are actually different, such as Figure 3 As shown, the reflection angle of the light transmitted in the diffraction waveguide substrate 10 corresponding to the parallel light S' will be inconsistent, which will affect the imaging. In order to solve this problem, in some embodiments, a light source with a smaller exit pupil is used, for example, a light source with a diameter of Φ1 to 2 mm. In some embodiments, a phase modulation device can also be added at the coupling region 20.

[0055] On the basis of the above embodiment, optionally, combined with Figure 4 As shown in (a), (b) and (c), the waveguide substrate also includes a phase modulation device 40. The light of the same field of view angle emitted by the optical machine is modulated by the phase modulation device 40 and then incident on the coupling-in area 20, so that the transmission angles of the light of the same field of view angle after being coupled into the curved waveguide substrate 10 are the same.

[0056] On the basis of the above embodiment, optionally, combined with Figure 4 As shown in (a), (b) and (c), the phase modulation device 40 includes a focusing lens 41, and the focusing lens 41 is arranged in the coupling area 20 or the exit pupil position of the optical machine; or, the right-angle surface of the turning prism 42 of the optical machine is a free-form surface, and the free-form surface is realized as the phase modulation device.

[0057] Specifically, the focusing lens 41 is located on the incident light path of the image light S, and is used to focus the image light S; the turning prism 42 is located on the incident light path of the image light S, and is used to deflect the propagation direction of the image light S.

[0058] In addition, when a diffractive optical element is used in the coupling region, according to the following grating equation (1.3), since the diffraction angles of image light of different wavelengths are different, the propagation angles of image light of different wavelengths in the curved waveguide substrate are different. The longer the wavelength, the larger the diffraction angle. The larger the angle of the blue light and the red light in the curved waveguide substrate is, the better the color uniformity is. In order to achieve better color uniformity, the embodiment of the present application proposes a diffraction waveguide using multiple curved waveguide substrates stacked together. Different curved waveguide substrates propagate light of different wavelengths. Among them, the grating equation (1.3):

[0059]

[0060] Where d is the grating period of the coupled grating, n air is the refractive index of air, n WG is the refractive index of the curved waveguide substrate, θ is the incident angle, is the diffraction angle, λ is the wavelength, the longer the wavelength, the larger the diffraction angle The bigger.

[0061] Figure 5 A schematic diagram of another curved waveguide structure provided in an embodiment of the present application. Figure 5 As shown, the curved waveguide provided in the embodiment of the present application includes a plurality of curved waveguide substrates 10 stacked in layers; the optical functional areas of at least two curved waveguide substrates 10 have different curvature radii, and the curved waveguide substrates 10 with different curvature radii propagate image light of different wavelengths.

[0062] Specifically, taking the superposition of two layers of diffraction waveguide substrates 10 as an example, Figure 5 Only two stacked curved waveguide substrates 10 are shown, which are the first curved waveguide substrate 11 and the second curved waveguide substrate 12, wherein there is a gap structure between the first curved waveguide substrate 11 and the second curved waveguide substrate 12, and the curvature radius of the first curved waveguide substrate 11 is recorded as r1, and the curvature radius of the second curved waveguide substrate 12 is recorded as r2. In some embodiments, the curvature radii of the first curved waveguide substrate 11 and the second curved waveguide substrate 12 are different, for example, r1<r2. In other embodiments, the curved waveguide may include more curved waveguide substrates.

[0063] As an example, a monochromatic light machine emits image light S 11 , another monochromatic light machine emits image light S 12 , image ray S 12 The wavelength λ 12 Greater than the image ray S 11 The wavelength λ 11 , that is, 12 >λ 11 , such as red-green light and blue-green light, using the first curved waveguide substrate 11 to propagate the image light S 11 , using the second curved waveguide substrate 12 to propagate the image light S 12Or, the first curved waveguide substrate 11 is used to propagate red light and part of green light, and the second curved waveguide substrate 12 is used to propagate blue light and part of green light; through this setting, the image light S 11 The image light S is coupled out from the outcoupling region of the first curved waveguide substrate 11. 12 The coupled light is coupled out from the outcoupling area of ​​the second curved waveguide substrate 12, and the outcoupled light is mixed to form an image display. The curved waveguide substrate with a larger curvature radius is used to propagate image light with a longer wavelength, which can better achieve color uniformity of image display.

[0064] Based on the above embodiments, continue to refer to Figure 5 As shown, along the direction in which the image light S is coupled out of the curved waveguide substrate 10, the curvature radii of the multiple curved waveguide substrates 10 gradually decrease, and the propagation wavelengths of the multiple curved waveguide substrates 10 gradually decrease.

[0065] For details, please refer to Figure 5 As shown, in order to make the structure of the waveguide substrate compact, multiple curved waveguide substrates 10 can be arranged in sequence, and a gap is set between two adjacent curved waveguide substrates 10. The concave surfaces of the multiple curved waveguide substrates 10 face the user's observation area. In this way, the curvature radius of the multiple curved waveguide substrates 10 is gradually reduced, and the curved waveguide substrate with a smaller curvature radius is used to propagate image light with a smaller wavelength. The propagation wavelengths of the multiple curved waveguide substrates 10 are gradually reduced to couple out image lights of different wavelengths to the user's observation area respectively.

[0066] Figure 6 A schematic diagram of another curved waveguide structure provided in an embodiment of the present application. Figure 6 As shown, along the direction in which the image light S is coupled out of the curved waveguide substrate 10 , the thickness of the plurality of curved waveguide substrates 10 gradually increases.

[0067] Specific, combined Figure 6 As shown, taking the superposition of two layers of diffraction waveguide substrates 10 as an example, Figure 6 Only two stacked curved waveguide substrates 10 are shown, which are the first curved waveguide substrate 11 and the second curved waveguide substrate 12. The thicknesses h1 and h2 of the two diffraction waveguide substrates are recorded. In some embodiments, the thickness of each curved waveguide can be different. The thickness of the curved waveguide substrate with a longer propagation wavelength is thinner. Figure 6 As shown, h1>h2 is set. This setting can better balance the color uniformity of the image display.

[0068] In addition, when the coupling region is a diffractive optical element and the scene is not monochromatic, the optical machine needs to be calibrated to compensate for the dispersion effect caused by the coupled diffraction. Specifically, the image lights corresponding to multiple monochrome images of different colors are projected respectively by a laser beam scanning optical machine, and the image lights are imaged and displayed after passing through the aforementioned curved waveguide; and when projecting image lights of any color among the image lights of multiple monochrome images of different colors, the scanning angle of the laser beam scanning optical machine is adjusted to make the display position of the monochrome image corresponding to the image light approach the target position. When the display position of the monochrome image corresponding to the image light reaches the target position, the corresponding scanning angle of each image pixel in the monochrome image corresponding to the image light is recorded; wherein the target position is the display position where there is no dispersion and no distortion in theory; multiple monochrome images of different colors are displayed as a color image when they overlap; the adjustment of the scanning angle is used to compensate for the dispersion and distortion caused by the diffraction of image lights of different colors.

[0069] Based on the above embodiments, continue to refer to Figure 1 and Figure 2 As shown, the surface of the outcoupling reflection surface 31 is coated with a filter film, and the filter film includes a monochromatic filter film or a filter film that transmits at least two colors.

[0070] Specific, combined Figure 1 and Figure 2 As shown, a filter film may be coated on the surface of multiple out-coupling reflective surfaces 31. In some embodiments, all the out-coupling reflective surfaces 31 may be coated with a filter film. For example, one or two of the red light, green light, and blue light may be selectively transmitted. The transmission (reflection) rate of the out-coupling reflective surface 31 may be improved by coating to enhance the image display effect.

[0071] Based on the above embodiments, continue to refer to Figure 1 and Figure 2 As shown, along the propagation direction of the image light S in the curved waveguide substrate 10, the reflectivity of the n outcoupling reflection surfaces 31 gradually increases.

[0072] Specifically, continue to combine Figure 1 As shown, in some applications, the diffraction waveguide can use a binocular single-optical machine, that is, the image light S emitted by the optical machine is coupled into the diffraction waveguide substrate 10 from the left and right sides of the diffraction waveguide, and the image light S is transmitted to both sides at the same time. At this time, the out-coupling reflection surfaces 31 at the left and right eyes are set to have opposite tilt directions. In order to avoid light crosstalk, a feasible implementation method is to modulate the reflectivity of the out-coupling reflection surface, such as the reflectivity of the out-coupling reflection surfaces on the left and right sides gradually increases to 100% as the distance from the coupling-in increases, so as to balance the light uniformity of the out-coupling area.

[0073] Based on the same inventive concept, an embodiment of the present application further provides a head-mounted display, comprising any curved waveguide provided in the above embodiments. Figure 7 A side view of a head mounted display provided in an embodiment of the present application; Figure 8 A top view of a head mounted display provided in an embodiment of the present application. Figure 7 and Figure 8 As shown, the head mounted display 300 further includes at least one optical engine 100 and at least one image collector 200; the image collector 200 is located to obtain peripheral images, and transmits the peripheral images through the optical engine 100 to the output end of the curved waveguide for display. Furthermore, the coupling region of the curved waveguide may be located at the side, top or back of the head mounted display 300;

[0074] Specific, combined Figure 7 As shown, the head mounted display 300 may be a helmet, which may be monocular or binocular, and the binocular may use a single optical machine 100 or a dual optical machine 100; when a binocular single optical machine 100 is used, the coupling region may be set at the rear side of the head mounted display 300, and the image light S may be transmitted to both sides at the same time, as shown in FIG. Figure 8 As shown, at this time, the out-coupling reflection surfaces at the left and right eyes are set with opposite tilt directions. In order to avoid light crosstalk, the reflectivity of the out-coupling reflection surface needs to be modulated, that is, the reflectivity of the out-coupling reflection surfaces on the left and right sides gradually increases to 100% as the distance from the coupling-in increases.

[0075] Combination Figure 7 As shown, the image collector 200 can adopt a high-definition small camera, and 1-3 cameras can be set at the rear of the helmet to shoot the road conditions behind, and at the same time transmit the photographed road condition information to the optical machine 100, and the optical machine 100 transmits the video image information to the output end of the waveguide substrate for display.

[0076] In summary, compared with traditional lens-type flat waveguides, the head-mounted display of the present application has a curved display structure, a larger usable area, and a larger image receivable range. The shape of the helmet also provides more possibilities for the installation location of the optical machine and circuit board, which is more beautiful, more flexible in design, and puts less pressure on the ears.

[0077] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and the features of the various embodiments of the present invention may be combined with each other in part or in whole, and may cooperate with each other in various ways and be technically driven. It is possible for those skilled in the art to make various obvious changes, readjustments, combinations and substitutions without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A curved waveguide, It is characterized in that The invention comprises at least one curved waveguide substrate and an in-coupling region and an out-coupling region located on at least one side of the curved waveguide substrate; In the same curved waveguide substrate, the coupling-in region, the coupling-out region and the region between the coupling-in region and the coupling-out region are optical functional regions, and the curved surface normal lines of the optical functional regions intersect at one point; The coupling-in region is used to couple the image light emitted by the optical machine into the curved waveguide substrate, and the image light is transmitted to the coupling-out region by total reflection in the curved waveguide substrate; the coupling-out region is located on the propagation path of the image light, and is used to couple the image light out of the curved waveguide substrate; Wherein, the out-coupling area includes n out-coupling reflection surfaces, wherein n≥2 and n is a positive integer; the n out-coupling reflection surfaces are sequentially located on the propagation path of the image light, and are used to couple the image light out of the curved waveguide substrate by partial reflection.

2. The curved waveguide according to claim 1, It is characterized in that The angle between the ith out-coupling reflection surface among the n out-coupling reflection surfaces and the surface normal passing through its reflection point is θ i : i i =θ i-1 +θ / 2;i=2,3,4,……,n; Among them, θ 0 is the angle between the image light and the normal after entering the curved waveguide substrate, r is the radius of curvature of the inner side of the curved waveguide substrate, and d is the thickness of the curved waveguide substrate; θ is the central angle of the image light with the same field of view corresponding to the reflection points of two adjacent out-coupling reflection surfaces inside the curved waveguide substrate. As the value of i gradually increases, the i-th out-coupling reflection surface gradually moves away from the coupling-in area.

3. The curved waveguide according to claim 1, It is characterized in that Along the propagation direction of the image light in the curved waveguide substrate, the reflectivity of the n out-coupling reflection surfaces gradually increases.

4. The curved waveguide according to claim 1, It is characterized in that The curved waveguide includes a plurality of curved waveguide substrates stacked in layers; The optical functional areas of at least two of the curved waveguide substrates have different curvature radii, and the curved waveguide substrates with different curvature radii propagate image light of different wavelengths.

5. The curved waveguide according to claim 4, It is characterized in that Along the direction in which the image light beam is coupled out of the curved waveguide substrate, the curvature radii of the optical functional areas of the plurality of curved waveguide substrates gradually decrease, and the wavelengths propagated by the plurality of curved waveguide substrates gradually decrease.

6. The curved waveguide according to claim 5, It is characterized in that Along the direction in which the image light is coupled out of the curved waveguide substrate, the thicknesses of the plurality of curved waveguide substrates gradually increase.

7. The curved waveguide according to claim 1, It is characterized in that It also includes a phase modulation device. The light of the same field of view angle emitted by the optical machine is modulated by the phase modulation device and then incident on the coupling-in area, so that the transmission angle of the light of the same field of view angle after being coupled into the curved waveguide substrate is the same.

8. According to the curved waveguide according to claim 7, the phase modulation device comprises a focusing lens, and the focusing lens is arranged in the coupling-in area or the exit pupil position of the optical machine; or, the right-angle surface of the turning prism of the optical machine is a free-form surface, and the free-form surface is realized as the phase modulation device.

9. A head mounted display, It is characterized in that A curved waveguide comprising the curved waveguide according to any one of claims 1 to 8, further comprising at least one optical machine and at least one image collector; The image collector is used to acquire the surrounding image, and transmit the surrounding image through the optical machine to be displayed at the output end of the curved waveguide.

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